1. Field of the Invention
The present invention pertains to a light-emitting diode, which is a light-emitting diode device comprising a light-emitting diode chip, particularly with which at least part of the light is converted in wavelength by a fluorescent material, making it possible to produce emission in a color that is different from the emission color of the light-emitting diode chip, for instance, white.
2. Description of the Related Art
A conventional example of a light-emitting diode of this type is described, for instance, in Japanese Patent Publication No. 8(1996)-320,656 and Japanese Patent Publication No. 11(1999)-251,640. According to the former document, the light-emitting diode device has a printed wiring board and a mask plate made of rubber or resin on top of this, and part of this mask plate comprises a cup that reflects light. The light-emitting diode chip is mounted on the inside of this cup. Light-transmitting filler is introduced and hardened inside the cup. Moreover, a lens plate of a pre-determined shape for focusing the light that has been emitted by the light-emitting diode is joined to the top of the mask plate.
A problem with this type of light-emitting diode is that a clearance or gap can be formed when air makes its way in between the lens plate and the filler and therefore, the luminous efficacy drops due to the effect of this air layer. It is all but impossible to eliminate the air layer when filler is introduced onto such a small surface area inside a cup and the lens plate is placed on top during the production process.
In order to eliminate this type of air layer, for instance, it is possible to further apply another filler over the first filler and form this into a lens shape. Nevertheless, as shown by the latter of the above-mentioned Patent Publications, using this type of process complicates production process and increases the cost of the product.
Moreover, another problem exists relating to wavelength conversion by the fluorescent material. According to the technique shown in the above-mentioned latter Patent Publication, a structure is used with which the emission from the light-emitting diode chip can be converted in wavelength. By means of the structure described in this patent, the resin material placed around the light-emitting diode chip contains a fluorescent material and this displays a color other than the original emission of the light-emitting diode chip when the emission from the light-emitting diode is converted in wavelength.
Nevertheless, this structure can produce irregularities in the light that is radiated to the outside due to the effect of differences in optical light paths emitted in each direction from the light-emitting diode chip, or a difference in the distribution of the fluorescent material. Moreover, fluctuations in the emission color between products are relatively large and there are cases in which these cause inconveniences, depending on the purpose for which the product is used.